Add Snap CI build status support

[tjrana]

I would like to suggest that Snap CI can also be integrated into this badges/shields project.

[espadrine]

Thanks for the suggestion!

[ghost]

👍

[pine]

👍

[kentcdodds]

Thanks @pine613! Any way we could get support for private repos as well? This would effectively turn this line

var url = 'https://snap-ci.com/' + userRepo + '/branch/' + branch + '/build_image.svg';

into this:

var url = 'https://snap-ci.com/' + repoToken + '/build_image.svg';

I'm not 100% certain that I know what needs to change though...

[espadrine]

@kentcdodds Thanks for indicating this! I assume repoToken is meant to be secret, which makes testing awkward. Copying the same Snap CI code in shields under a different URL (say, /snap-ci/private/TOKEN.svg) ought to work?

I made a bit of a mistake during the review by not requiring /snap-ci/ci/user/repo.svg, but I hope it won't hurt too much in the future.

[kentcdodds]

Unfortunately snap-ci/private/TOKEN.svg doesn't currently work (were you saying that it would?)

[espadrine]

It doesn't, but it is a plausible Shields URL if it were to be implemented.